The .json file is what Rpg Maker uses internally to load the map into a project. Search for "how to import a map in RPG Maker MV" and you'll find plenty of guides on how to do it.
Viewing post in Ysmael - Map Resource for RPG MAKER MV comments
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1. Nice that you get them Advice to how Import your map and Tips how to find a Guide for it
2. What People dislikes this? they literally just ask a Question about something they start to learn/not known already... I lose hope in Humanity when i see that People got Disliked just cause they dont know something...